Disinfection of sewage sludge cake by an electron accelerator

The effects of fly-ash on dewatering of sewage sludge were studied according to sludge specific resistance (SSR), dehydrated speed, and moisture content of sludge cake as investigation indexes through single-factor experiments by contrasting to cationic polyacrylamide (PAM). The results showed that SSR kept decreasing with the rising of fly-ash dosage. When the dosage of fly-ash was 0.02 g/(ml sludge), SSR reduced by 65.2%. When the dosage of fly-ash was over 0.03 g/(ml sludge) adding with PAM, the dehydrated speed will be increased by three fourths. Through the analyses of Zeta potential, scanning electron microscope (SEM) observation, combined with the dehydration experiments, it was thought that the mechanism of fly-ash on dewatering of sewage sludge was that their particles evenly dispersed in sludge floc skeleton structure and thus decreased the SSR and improved the permeability of the sludge cake. The disposal of dewatering sludge and recycling approaches after fly-ash condition were also discussed. They can be used as landfill or as raw materials in building fields.

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Parameter investigation for decentralised dewatering and solar thermic drying of sludge

Water Science & Technology ◽

10.2166/wst.2005.0352 ◽

2005 ◽

Vol 51 (10) ◽

pp. 65-73 ◽

Cited By ~ 5

Author(s):

B. Wett ◽

M. Demattio ◽

W. Becker

Keyword(s):

Sewage Sludge ◽

Initial Conditions ◽

Simulated Data ◽

Field Tests ◽

High Water ◽

High Water Content ◽

Secondary Importance ◽

Initial Height ◽

Sludge Cake ◽

Slurry Layer

The purpose of this paper is an experimental and model assisted investigation of the capabilities of a dewatering system for sewage sludge for decentralised sites. Laboratory and field tests are performed with different initial conditions and the influences of filter medium, initial height, initial total suspended solids, temperature and relative humidity are discussed. The experimental work shows the feasibility of geotextile media for dewatering high water content sewage sludge and that the textile structure is of secondary importance. The specific filter resistance of the sludge cake is found to be the most significant factor in dewatering applications. The mathematical description of the dewatering process is based on the superposition of two models, the Conventional Filtration Theory for the filtration phase and the BT-model for the drying phase. Feasibility and limits of the theoretical approach are evaluated by means of a comparison between measurements and simulated data of cyclic reloading tests. It is found that a better filtration efficiency is achieved at higher TSS and at lower initial height of the slurry layer. Due to the viscosity decrease, a higher temperature enhances not only evaporation, but also filtration rate.

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Bacteriological analysis of stored aerobic sewage sludge cake

Agricultural Wastes ◽

10.1016/0141-4607(86)90080-6 ◽

1986 ◽

Vol 16 (2) ◽

pp. 77-87

Author(s):

Salwa K.A. Al-Azawi

Keyword(s):

Sewage Sludge ◽

Bacteriological Analysis ◽

Sludge Cake

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The effect of biosolids on cereals in central New South Wales, Australia. 1. Crop growth and yield

Australian Journal of Experimental Agriculture ◽

10.1071/ea03099 ◽

2005 ◽

Vol 45 (4) ◽

pp. 435 ◽

Cited By ~ 10

Author(s):

J. L. Cooper

Keyword(s):

Sewage Sludge ◽

Soil Ph ◽

New South ◽

New South Wales ◽

Acid Soils ◽

Crop Growth ◽

Growth And Yield ◽

South Wales ◽

Sludge Cake ◽

Dewatered Sewage Sludge

Two forms of biosolids, with and without lime, were applied to acid soils at 2 sites in central New South Wales. Wheat and triticale were then grown on these sites to determine the effect of biosolids on crop growth and yield. The forms of biosolids used were dewatered sewage sludge cake, and N-Viro Soil which is a lime amended sewage sludge. Dewatered sewage sludge cake was applied at rates of 0, 6, 12 and 24 dry Mg/ha, and N-Viro soil at 0, 1.5, 3.0 and 4.5 dry Mg/ha. Biosolids produced grain yield increases of over 50% at both sites, with the largest yield increases at the highest rate of dewatered sewage sludge. Continued cropping at 1 of the sites showed that significant yield increases were still obtained 3 years after the initial application. The addition of lime and N-Viro Soil raised soil pH, and produced small but long lasting yield increases. However, the main benefit of biosolids seems to have come from the nutrients they supplied rather than changes in soil pH.

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Characteristics of Sewage Sludge Affecting Dewatering by Belt Press Filter

Water Science & Technology ◽

10.2166/wst.1990.0109 ◽

1990 ◽

Vol 22 (12) ◽

pp. 143-152 ◽

Cited By ~ 6

Author(s):

M. Hashimoto ◽

M. Hiraoka

Keyword(s):

Sewage Sludge ◽

Moisture Content ◽

Charge Density ◽

Suspended Solids ◽

Factors Affecting ◽

Solids Concentration ◽

Sludge Cake ◽

Extension Degree ◽

Dewatered Sludge ◽

Belt Press

Dewatering characteristics of sewage sludge were determined by conditioning the sludge with the most effective cationic polyelectrolyte studied, and dewatering using a belt press filter. The characteristics of sludges (16 mixed, and 8 anaerobically digested) were measured for 33 factors affecting dewaterability. The correlations of sludge factors with sludge dewaterability were investigated. The results revealed the following. A factor affecting the gravitational filterability of conditioned sludge is the suspended solids concentration of raw sludge. A factor affecting the moisture content of dewatered sludge cake is viscosity of the sludge adjusted to 4.0 % of suspended solids concentration. Factors affecting the viscosity are the intrinsic viscosity of alkaline extracts, the ratio of (VSS-Fiber)/SS : Ash/SS : Fiber/SS, and the charge density of sludge particles. A factor affecting the extension degree of dewatered sludge cake is the charge density of sludge particles. Factors affecting the amount of residual solids on the filter cloths are the charge density of sludge particles and the fibrous substances content of sludge. As for polyelectrolytes, a highly cationized polyelectrolyte is effective to lower the moisture content, the extension degree and the amount of residual solids on filter cloths. And a factor affecting the required dosage of a polyelectrolyte is anionic substances content in the liquid of raw sludge.

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Prediction of full-scale dewatering results of sewage sludges by the physical water distribution

Water Science & Technology ◽

10.2166/wst.2001.0676 ◽

2001 ◽

Vol 43 (11) ◽

pp. 135-143 ◽

Cited By ~ 19

Author(s):

J. Kopp ◽

N. Dichtl

Keyword(s):

Sewage Sludge ◽

Water Content ◽

Water Distribution ◽

Free Water ◽

Full Scale ◽

Water Release ◽

Total Solids ◽

Solids Concentration ◽

Free Water Content ◽

Sludge Cake

The dewaterabilty of sewage sludge can be described by the total solids concentration of the sludge cake and the polymer-demand for conditioning. The total solids concentration of the sludge cake depends on the physical water distribution. The various types of water in sewage sludge are mainly distinguished by the type and the intensity of their physical bonding to the solids. In a sewage sludge suspension four different types of water can be distinguished. These are the free water, which is not bound to the particles, the interstitial water, which is bound by capillary forces between the sludge flocs, the surface water, which is bound by adhesive forces and intracellular water. Only the share of free water can be separated during mechanical dewatering. It can be shown, that by thermo-gravimeteric measurement of the free water content, an exact prediction of full-scale dewatering results is possible. By separation of all free water during centrifugation the maximum dewatering result is reached. Polymer conditioning increases the velocity of the sludge water release, but the free water content is not influenced by this process. Furthermore it is not possible, to replace the measuring of the water distribution by other individual parameters such as ignition loss.

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Analaysis of volatile odour compounds in digested sewage sludge and aged sewage sludge cake

Water Science & Technology ◽

10.2166/wst.2000.0095 ◽

2000 ◽

Vol 41 (6) ◽

pp. 73-80 ◽

Cited By ~ 4

Author(s):

P. Winter ◽

S. C. Duckham

Keyword(s):

Sewage Sludge ◽

Sewage Treatment ◽

Threshold Concentration ◽

The Other ◽

Gas Chromatography Mass Spectrometry ◽

Treated Sewage ◽

Odour Threshold ◽

Sludge Cake ◽

Digested Sewage Sludge ◽

Purge And Trap Sampling

A number of malodorous compounds were identified in digested sludge and the corresponding sludge cakes. The major components included a number of sulfides. The levels of these compounds were monitored in order to investigate the influence of the sludge treatment process and length of cake storage on the malodour of treated sewage sludge. Two sewage treatment works (STWs) were surveyed. One of the works (Site B) produced very malodorous sludge cake, whilst the other produced a much less odorous cake (Site A). The analysis consisted of purge and trap sampling of liquefied samples followed by gas chromatography-mass spectrometry (GC-MS). Afteran initial screening of samples, by full mass scan GC-MS analysis, targetcompounds were identified for quantification. Sulfide levels inthe majority of the liquid digested sludges were significantly lower than that in sludge cakes. Large differences in the level of sulfides were found in stockpiled sludge cakes. The majority of malodorous sludge cakes had higher sulfide levels than less odorous sludge cakes. The most abundant compounds were dimethylsulfide, dimethyldisulfide and dimethyltrisulfide. Thehighest sulfide levels were found during the first month of stockpiling. Whenthe odour threshold concentration of these compounds was taken into account and odour unit values were calculated, dimethyltrisulfide was found to have a proportionally greater impact on odour than any of the other compounds studied. The use of sulfide levels as indicators of malodour formation and possible strategies for reducing odour in stockpiled sludge cake are discussed.

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Improvement of sewage sludge dewaterability by bioleaching in a continuous plug flow bioreactor: optimization of process parameters

Water Science & Technology ◽

10.2166/wst.2018.083 ◽

2018 ◽

Vol 77 (8) ◽

pp. 1979-1989 ◽

Cited By ~ 3

Author(s):

Jingqing Gao ◽

Na Ma ◽

Linshuai Li ◽

Songfeng Zhu ◽

Yonghong Li ◽

...

Keyword(s):

Sewage Sludge ◽

Moisture Content ◽

Plug Flow ◽

Aeration Rate ◽

Acidithiobacillus Thiooxidans ◽

Optimization Of Process Parameters ◽

Working Volume ◽

Sludge Cake ◽

Sludge Dewaterability ◽

The Impact

Abstract A novel process for sewage sludge bioleaching by mixed Thiobacilli (Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans) using a 12-stage, 180 L working volume continuous plug-flow bioreactor, is presented. The objective of the present study was to assess the impact of some parameters on the sludge dewaterability and to improve the sludge dewaterability by optimization of these parameters. The parameters examined were sludge moisture content, nutrients dosage, aeration rate, and the number of reactors. The order of the influence of these factors on sludge dewaterability was found to be sludge moisture content > nutrients dosage > aeration rate > number of reactors. The optimized conditions were: sludge moisture content, 98.0%, nutrients dosage, 9 g/L, aeration rate, 8 m3/h, and 10 reactors. Confirmation experiments conducted under optimum conditions demonstrate the sludge dewaterability to be remarkably improved. After 2 days of bioleaching, the moisture of bioleached sludge cake was reduced to below 60%.

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